I've got a '70 442 w/A/C and need to get a new under dash heater core box. Does anyone know what years and if it interchanges w/other GM A-bodies that year(s)?

 

I was all set to say that the 68-72 A-bodies use the same firewall and HVAC box, however the parts book shows different P/Ns for 68-69 and 70-72 F-85 series. The heater core is the same, however. Apparently the differences are in the vacuum valves and flapper doors. I SUSPECT (but don't know for sure) that you can swap the entire assembly as a unit. Of course, the ducting that bolts to the box is unique due to dashboard and vent configurations.

 

Joe, Thanks so much. I've got a A/C heater box assembly out of a 72 Cutlass S that I wanted to check to see if that works...looks like it will match up with the outside condenser box. Whew! Always interesting seeing what will interchange and what won't.